In the electronic packaging industry, printed circuit board (PCB) assemblies having electrical components mounted thereon are tested against drop impact by the typical board-level drop test, whereby a board assembly is dropped from a certain height and experiences a sharp acceleration pulse upon impact. The main focus of the drop test is to assess the reliability of the interconnectors, which provide the physical and electrical connection between the PCB and the electrical components mounted thereon.
It has been found that the major failure driver in these tests is the free vibrational flexing of the PCBs after impact. It is also recognized that the drop test method is time-consuming owing to the time required to raise the board assembly to the drop height and the quantity of drops required in standard testing. The drop test method is also inconsistent owing to the high accelerations and forces causing loosening of screws and wear of mechanical fixtures. An effective solution to these problems would be a bend test which performs bending at the free vibration frequencies of PCB assemblies which range from 200 Hz to 1000 Hz at accelerations of up to 3000 g (where g is the acceleration due to gravity) taken at the mid-point of the PCB. Such a test should be able to cut testing times by a factor of at least 20 and should also be more controllable and consistent owing to the absence of the large impact forces on the fixtures. Examples of such bend testers and methods for simulating the free vibrational flexing of PCBs include electromagnetic shakers and universal static testers, for example. However, these testers do not comply with the above-mentioned frequency and acceleration requirements.
Existing equipment and methods for including bending loads are, as mentioned above, inadequate for reproducing the bending frequencies of a test specimen subjected to drop testing. The universal static test has a maximum test frequency of only several Hertz (Hz), and present electromagnetic shakers fall far short of the required 1000 Hz and 3000 g flexural vibration requirements.
Therefore, there is a need for a high-speed bend tester that is capable of simulating flexure over a wide range of frequencies at accelerations of up to several thousand g's and that is cost effective to produce and operate as well.